mocallum



2 Sheets-Sheet 2. C. J. MOCALLUM. Rotary-Valve for Steam-Engines.

Patented Sept. 16, 1879.

N. PE'ERS, FHOTO-UTHOGRMNER. WKSHINGTON. D C.

UNITED CHARLESJ J'. MCOALEUM, -F WARREN, MAINE.

I M"P"R`O"V E M ENT IN* R O F'A-RY VWEV ES FO R S 'FEA M -E N G IN ES.

Specification forming part of Lettersl fatent` N'o. %IQ-.3 50, dated September 16, 1879; application filed August 15, 1879.

To all whom 'it may concem:

Be it known that LGHARLES J. MGGALLUM, of Warren, county of Knox, State of Maine,

have invented -an Improvement in Rotary Valves for Steam-Engines, of which the following is a specification.

My invention relates to rotary valves for steam engines of that class in which the valves are made hollow, with slots or openings in'the shell of the valves to form ports for the in gress and egress of the steam.

The objectcf the'invention is to gai1simplicity in construction with eapability of working the steam expansively, and especially to provide such a construetion that the steam may be admittedin successivo instalnents during the stroke.

The details of my invention are herein fully explained, and the eXteut of said invention indicated in the claims.

In the drawings hereunto attached and forning part of this specifieation, Fgure 1 is a perspective VGW of my improvement with the valves in position; Fig. 2, a transversevertical section centrally through the valve-seat and valve, and through the connectios With the cylinder. Fig. 3 is a central transverse section across the axis of the valve, showing the oylinder-connections in part and thesupply and exhaust pipes, also in part. F'g. 4 is asperspective View of thevalve removed from its seat.

In Figs. 1, 2, and 3, A represents the Valveseat, and B G the connections with the cylinder, said connections opening into the Valveseat through slots b c. Also connected to the vaIve-seat at right angles to the pipes B C are the supply and exhaust pipes, marked E and F, respectively, the pipes E and F having openings into -the valve-seat, marked respectively, e and f.

The interier surface of the valve-seat A is turned smooth and true, and preferably slightly conical to obtain a close fit and compensate for wear, and the valve is fitted accurately thereto. The valve is represeuted in Fig. 4, and is marked Gin this and the other figures.

It is in form frusto-c'onical, (slightly taper-.

ing,) is made hollow, and closed at the ends. A central partition, g, extending aXially from side to side throughout the entire length of the valve, divides it into two equal chanbers.

V These chambers` are provided with openings or ports m m m 0 o' o 'pp p q q' q", all in i length and width corresponding exactly to the ports b c and ef..

The axis ofthe valve is shown at H. It

extends through the heads of the valve and i through stuffingboxes in the: heads of the valve seat or chest, and is connected 'to suitable gearing in order to impartproper rotary motion to the valve. This motion is so regulated that the valve shall make one quarter revolution during one stroke of the pisten, and there being three slots in one-quarter of the circumference of the valve, as m m' m", there will be three successive instalnents or impulses of the steam during each stroke of the piston. The arrangenent of the parts and their operation may be understood by reference to Fig. 3.

The valve being in the position there shown in full lines, the pisten will be understood as at the beginning of its stroke, and, movin g to the left, steam is admitted through' the supply-pipe E and through the port q", and passes to the cylinder through the port 10" or pipe c. The supply of stean is, however, cut off for an instant, in the forward movement of the valve, by the bar or cut-off 11. This, like all the ,other-s, is made a little wider than the opening, in order to give full opportunity to allow the steam to work expansively. While the port q" is open, however, the other end of the cylinder is exhausting through the pipe B, openings in port m", and by port 0", through ,exhaust-pipe F. At the next step the live steam is admitted at q' and the exhaust escapes at o', and at the third andlast in this stroke the steam is admitted through q and exhausted through 0. At this instant the edge 12 of the partition g will be passing the stean-port c, when live steam will be cut off', the other end 6 of partitio'n g will pass the exhaustport f, and allow that end of the cyl inder to which the pipe e is attached to ex haust through the proper openings. The partition g all the while separates the live stean from the dead, the edges 6 and 12 acting in their turn to cut ofi' the steam-from either end of the cylinder in the same manner as the bars l and 2, 850., all being of the same width.

It will be observed that this Construction of the valve Supplies the steam to the cylinder in quick instalments 01` inpulses and then allows it to Work expansively.

In the arrangement shown, the stcam is admitted at the beginning of the stroke, again at half-stroke, when it has the greatest leverage, and again a little before the piston reaches the center, which carries it past the center.

It is obvious that the number of ports may be increased and the steam admitted in smaller and more frequent instalments, but obviously a less number than that shown cannot be used, When the stean is tobe admitted by instalments. I oontemplate also connecting the valve to the driving-shaft by means of a starwheel, iuterposed in suitable position, in order to give an intermittent or step-by-step movement to the valve, such movement being so regulated as to admt the steam sucoessively through the ports and, by means of the bars 1, 2, 3, &(3., to cut ofi the steam and allow it to work expansively, as heretofore explaied.

The shell of the valve-chest may be inclosed in another casing, the supply-pipe terninatin g in the said onter shell and supplyimg said intervening space with steam.

Having thus described my invention, what I claim, and desire to secure by Letters Patent of the United States, is-

In a rotary Valve constructed to make onefourth revolution to each stroke, the combinetion of the shell, slotted with ports and interposed bars, to give successive instalments of steam during each stroke, and of the trans- Verse partition g, with the valve-seat and ports therein, as and for the purposes shown.

In testimony whereof I have signed my name to this specification in the presence of two subscrihing witnesses.

CHARLES J. MCOALLUM.

Witnesses:

F. L. MIDDLETON, W. C. MARTIN. 

